Post-Mortem Redistribution
Definition
The movement of drugs from solid tissues into central blood after death, due to diffusion along concentration gradients, autolytic enzyme release, and microbial action. Redistribution can elevate central blood drug concentrations several-fold above ante-mortem levels, complicating both immunoassay screening and quantitative chromatographic interpretation.
- Field
- Forensic toxicology
- Mechanism
- Diffusion, autolysis, microbial action after death
- Direction
- Solid tissue into central blood
- Effect
- Can elevate central blood levels several-fold
- Mitigation
- Sampling peripheral blood instead of central/cardiac blood
Common questions
Why do toxicologists prefer peripheral blood over central blood for quantitation?+
Central or cardiac blood sits closest to organs like the liver and stomach where drug concentrations are highest, so it is most affected by post-mortem redistribution; peripheral sites such as the femoral vein are further from those reservoirs and give a result closer to the ante-mortem level.
Does post-mortem redistribution affect all drugs equally?+
No. Drugs with a large volume of distribution and high tissue binding, common with many basic lipophilic drugs, redistribute more than drugs that stay mostly in plasma, so the size of the effect depends heavily on the specific substance being measured.
How does redistribution complicate interpreting a toxicology report for a court?+
A measured concentration that looks toxic on paper may partly reflect post-mortem movement rather than the level actually present at the time of death, so an experienced toxicologist has to account for sample site, time since death, and the drug's known redistribution behaviour before offering an opinion on impairment or cause of death.
Related terms
- Acid Fraction
- The organic phase recovered when the biological aqueous is acidified to pH 2 to 3 and shaken with diethyl ether or chloroform....
- Alkaline Fraction
- The organic phase recovered when the aqueous is basified to pH 9 to 10 with ammonium hydroxide or sodium hydroxide and shaken...
- CEDIA (Cloned Enzyme Donor Immunoassay)
- A homogeneous immunoassay using two inactive fragments of beta-galactosidase, an enzyme donor (ED) fragment conjugated to drug, and an enzyme acceptor (EA)...
- Cross-Reactivity
- The capacity of an antibody raised against one analyte to bind structurally related compounds. In RIA, cross-reactivity is the main driver of...
- Cut-Off
- The minimum analyte concentration that an SFSL reports as positive. SAMHSA-style serum cut-offs commonly used at Indian labs include morphine 2 ng/mL,...
- Cut-Off Concentration
- The threshold analyte concentration, set by regulatory guidance, above which a specimen is reported as a screen-positive. Choosing the cut-off balances sensitivity...
- DFC
- Drug-facilitated crime, the umbrella term for sexual assault, robbery or kidnapping in which a victim has been incapacitated by a clandestinely administered...
- EMIT (Enzyme-Multiplied Immunoassay Technique)
- A homogeneous competitive immunoassay in which drug in the sample competes with enzyme-labelled drug conjugate for antibody binding sites. Free enzyme-labelled conjugate...
- Lateral-Flow Immunoassay
- A point-of-care competitive immunochromatographic format on a nitrocellulose strip. In the absence of drug, colloidal gold-labelled antibody is captured at a test...
- Neutral Fraction
- The organic phase recovered when the aqueous is buffered to pH 7 to 9 and extracted with a less polar solvent like...
- pKa
- The negative logarithm of the acid dissociation constant. For a basic drug it is the pH at which half the molecules are...
Explained in these topics
- Acidic, Neutral and Alkaline Drug AnalysisThe shift of basic, lipophilic drugs (notably tricyclics, amitriptyline above all) from organ stores into central blood after death, which raises central blood...
- Immunological Drug Testing: Screening and Forensic Interpretation